How to remove water hardness?

Question

ahsome · Answer

Can you use $Ca(OH)_2$ in removing both Temporary and Permanent Hardness?

aaronq · Answer

so hardness is caused by $Ca^{2+} ~and~ Mg^{2+}$ ions in solution, you could in fact remove (precipitate) them by using a hydroxide base, but i dont know how practical that is. I think using an ion exchange resin is a better option, but i'm not sure

ahsome · Answer

It is. But we need someway we can use it in the lab, @aaronq, with primative equipment. I was just wondering if that substance removes both permanent and temporary hardness. Some sources say no, some say yes :(

aaronq · Answer

well, the base will get used up, so it wont be permanent, unless it is continuously being dispensed

ahsome · Answer

Permanent hardness is one that doesn't remove from boiling, right?

prakharluv · Answer

By boiling Hard water, we can remove its Hardness
$$Ca(HCO _{3})_{2} \rightarrow CaCO _{3} +H _{2}O + CO _{2}$$
On boiling, calcium/magnesium bicarbonate decomposes to give

calcium/magnesium carbonate, which is insoluble in water. Therefore, it precipitates out.

prakharluv · Answer

And by adding washing soda (sodium carbonate), you can remove both temporary as well as permanent hardness.

ahsome · Answer

@prakharluv, can the initial substance remove permanent hardness aswell?

prakharluv · Answer

No, by boiling hard water we can only remove its hardness(Carbonates) temporarily